Locking device for the spindle drum of an automatic multi-spindle lathe



Oct. 13, 1959 s. MATLACHOWSKY 2,908,357

LOCKING DEVICE FOR THE SPINDLE DRUM OF AN AUTOMATIC MULTI-SPINDLE LATHE Filed Dec. 20, 1956 INVENTOR Slap/1 an Ja/Imowly BY @JMKJ United States Patent LOCKING DEVICE FOR THE SPINDLE DRUM OF AN AUTOMATIC MULTI-SPINDLE LATHE Stephan Matlachowsky, Gntersloh, Westphalia, Germany, assiguor to Alfred H. Schutte, Koln-Deutz, Germany, a German company Application December 20, 1956, Serial No. 629,735 Claims priority, application Germany December 22,1955

6 Claims. (Cl. 188-69) The present invention relates generally to automatic multi-spindle lathes and, more particularly, is directed to a locking device for holding the spindle drum of such a lathe in any of the indexed positions thereof.

In existing multi-spindle automatic lathes, the spindle drum, which is indexed from one position to the next position after each operation, is locked in position during each operation by one or more locking pins, and the latter are engaged before the various tools start working on the work pieces in the individual spindle positions. Withdrawal of the pins from the cooperating notches of the drum is usually controlled by positively actuated members, whereas the pins are urged into the locking notches by springs or other resilient elements. While the spindle drum is in a working position, the pins remain spring-loaded.

The known devices for locking spindle drums in place have various disadvantages.

If only one locking pin is used, it is best located above the spindle drum, so that the spring pressure on the single pin then acts in the same direction as the weight of the drum. In other known designs the locking pin engages the drum in a horizontal plane, that is, at right angles to the. vertical central plane of the drum. In both cases, substantially only the weight of the drum is utilized to resist the forces resulting from the attack and the advance of the tools. These locking pins actually only determine the radial position of the spindle drum. The pressures exerted by the attack and advance of the tool carrying cross slides are applied predominantly at angles, even at right angles, to the vertical central plane of the spindle drum. A single locking pin located at the top has the advantage, therefore, of at least absorbing those pressures applied at an angle against the upper part of the drum. Thelower part of the drum, however, is fixed in a rather uncertain manner. It must not be overlooked that a certain play in the drum bearings cannot be avoided. Thus, the lower part of the spindle drum is always more or less misaligned by laterally acting forces when this design is used.

When two lock pins have been used in existing automatic multi-spindle lathes, they have been usually located in the horizontal central plane on either side of the drum, with one of the pins preventing rotation of the drum and thereby acting as a stop, while the second spring-loaded bolt or pin is radially pressed against the drum to hold the latter against the stop by a wedge effect or by means of resilient elements. This arrangement practically clamps the drum in the drum housing. It should be noted that such clamping may readily cause distortion of the precisely machined delicate spindle drum. As the locking pins extend predominantly in the same direction as the pressures exerted by attack and advance of the cross slides, the drum is held in position against such pressures, not by the direct shear resistance of the locking pins, but more or less by the friction between the pins and notches. In order to achieve adequate locking the pressure applied to the locking pins must be very high.

It is an object of the present invention to overcome the disadvantages of the known locking devices for drumsof multi-spindle automatic lathes.

According to an aspect of this invention, the drum is held in each indexing position 'by two pins engageable radially in notches in the drum. However, the two locking pins are arranged in the vertical central plane of the drum, one acting from above and one from below. Preferably, each pin has sloping or converging contact surfaces symmetrically arranged on both sides and forming the same angle with the longitudinal axis of the pin. Since the locking pins are identical with each other, they are adapted to engage the same series of notches or grooves formed in the spindle drum. Further, it is preferable to have the lower locking pin initially released to first engage the drum after indexing of the latter and to have the lower pin pressed against the drum by a weaker spring than the upper pin which is permitted to fall into place only after the lower pin has been engaged.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of an illustrative embodiment thereof which is to be read in connection with the accompanying drawing forming a part hereof, and wherein:

Fig. 1 is a diagrammatic transverse sectional view taken through the working space of an automatic multispindle lathe and looking towardsthe spindle housing thereof, with portions of the spindle housing and drum being shown broken away and in section to disclose the details of a locking device embodying the present invention; and

Fig. 2 is a side elevational view of the portion of the lathe of Fig. 1 having the locking device associated therewith.

Referring to the drawing in detail, .it will be seen that the illustrated automatic multi-spindle lathe, as usual, includes a spindle housing 10 having a drum 11 rotatably mounted therein and carrying a circularly arranged series of work spindles 12 which extend parallel to the axis of drum 11 and are uniformly spaced apart. In the illustrated lathe, six work spindles 12 are provided on the drum 11 and, accordingly, six working stations are provided around the perimeter of the spindle drum, a cross slide with an adjustable stop 13 being disposed at each working station to determine either the path of a tool, (not shown) or the extreme positions of the latter, employed for performing a turning operation on a work piece carried by the spindle which is then located at the related Working station. Thus, six different operations can be performed at the six working stations with each work piece being successively subjected to;the six different operations as the drum 11 is indexed through an angle of 60 degrees after the completion of eachv working phase.

In order to securely hold the drum 11 in a position where all of its spindles 12 register with working stations at the completion of an indexing movement of the drum, a locking device embodying the present invention is associated with the spindle drum 11 and the housing 10.

This locking device includes lower and upper locking pins 14 and 15, respectively, which are engageable radially from below and above, respectively, in recesses 16 and 17 opening radially outward in the outer peripheral surface of the drum 11, with the pins 14 and 15 being yieldably urged toward the axis of the spindle drum by helical compression springs 18 and 19, respectively.

As seen in Fig. l, the locking pins 14 and 15 have their axis aligned and disposed in the vertical central plane of the drum 11. In the illustrated embodiment of the invention, the pin 14 is axially slidable in a body 20 which Patented Oct. 13, 1959 7 has a tapering outer surface and which is received in a correspondingly tapered' bore 21 in the housing 10 opening radially inward at the cylindrical surface of the drum 11 and registering, in the axial direction, of the latter, with a circumferential series of recesses, including the recesses 16 and 17 referred to above, which are formed in the cylindrical surface of the spindle drum. The body 20 may be held in the tapered bore 21 by bolts 22 which extend through a mounting plate 23 on the outer surface of housing 10 and are threaded into the body 20. The structure movably supporting the upper locking pin 15 may be identical to that described above with reference to the pin 14 and, therefore, includes a body 24 having the pin 15 axially slidable therein and received in a tapered bore 25 in housing 10, with bolts 26 being mounted in a plate 27 on the housing 10 and threaded into body 24 to hold the latter against movement in its bore 25.

Further, as seen in Fig. 1, the pins 14 and 15 have recesses 28 and 29, respectively, therein opening axially at the ends of the pins remote from the drum 11, and the springs 18 and 19 are received in the recesses 28 and 29 to be guided by the latter while the ends of springs 18 and 19 projecting from the related recesses bear against the plates 23 and 27, respectively.

Although the pins may be either polygonal or round in cross-section, the inner ends of the pins 14 and 15 are wedge shaped or tapered so that at least their lateral surfaces converge in the longitudinal direction toward the center of drum, with the angles between such lateral surfaces and the vertical central plane of the drum being equal, and the recesses 16 and 17 of the drum are correspondingly wedge shaped so that, although the pins 14 and 15 can be easily inserted in, and removed from, the notches 16 and 17, substantially no clearance will exist between the lateral surfaces of the notches and of the corresponding locking pins when the latter are fully seated in the recesses by the action of the springs 18 and 19.

Of course, the notches in the cylindrical surface of drum 11 are spaced apart circumferentially so that, in any of the six working positions of the spindle drum, a notch 16, at the bottom of the drum, will register with the pin 14 and a notch 17, at the top of the drum, will register with the pin 15.

Preferably, the spring 18 urging the pin 14 upwardly into notch 16 is a relatively light or weak spring, while the spring 19 is a relatively strong spring and exerts a correspondingly strong force to urge the pin 15 into notch 17.

It is to be understood that the pins 14 and 15 have conventional control mechanisms (not shown) associated therewith and operative to withdraw the ends of the locking pins from the recesses of the drum, in order to permit indexing movement of the latter and, upon the completion of the indexing movement, to permit the springs 18 and 19 to return the locking pins 14 and 15 to their operative positions engaged in the recesses of the drum then registering with the locking pins. Preferably, such conventional control mechanisms are arranged so that, when an indexing movement of the drum 11 is completed, the pin 14 is first released to be urged by spring 18 into notch 16, thereby to center the lower part of the drum. Thereafter, the control mechanism releases pin 15 and the strong spring 19 then pushes the pin 15 into recess 17. By reason of the wedge shaped configurations of the recesses and of the ends of the pins received therein, and the fact that spring 19 exerts a greater force than spring 18, the excess force of spring 19, after pin 15 is fully seated in recess 17, acts downwardly along with gravity to seat the lower surface of drum 11 against the bottom of the cylindrical bore of housing 10 in which the drum is normally rotatable, thus removing any vertical play from the mounting of the drum. Further, it will be apparent that, during the movement. of the wedge shaped end, ofpin 15 nto e ess 1 the engagement of the inclined lateral surfaces of the pin and recess will cause the upper part of the drum 11 to be accurately centered.

It will be understood that the desired sequential engagement of the pins 14 and 15 is repeated for each working position of the drum 11 so. that, whenever working operations are being performed On Work pieces clamped to the spindles 12, all lateral and vertical play is removed from the rotational mounting of the drum, thereby to precisely define the positions of the spindles with respect to the cross slides and stops 13 at each Working station. It will be observed that the pressures exerted on the drum 11 as a result of the attack and advance of tools on the cross slides 13 are directed at angles as large as degrees with respect to the vertical plane through the axes of the pins 14 and 15 so that such pressures are absorbed by shear loading of the pins 14 and 15 and have practically no tendency to withdraw the pins from the related recesses 16 and 17. Since roughing operations are usually performed at the lower working stations with the cross slides there lo'cated being horizontally movable, as appears in Fig. 1, the heaviest pressures upon the drum act at right angles to the vertical central plane thereof and are easily absorbed by the lower pin 14. Further, the cross slides at the upper stations preferably move along downwardly inclined paths during advance or attack so that the resulting pressures on the drum have downward components which cannot disturb the alignment of the drum, as the latter is already firmly seated against the bottom of the housing 10.

Although an illustrative embodiment of the invention has been described in detail herein with reference to the accompanying drawing, it is to be understood that the invention is not limited to that particular embodiment and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention, except as defined in the appended claims.

The pins 14 and 15 can for example be actuated by the control shaft 30 which carries a cam disk with a cam 31. As the shaft 30 rotates this cam 31 first disengages the pin 14 through the intermediary of the twoarmed lever 32 and the pin 15 is only disengaged later through the intermediary of the link system 33, 34, 35. The subsequent reengagement of the pins 14 and 15 is effected successively in a similar manner by means of the cam 31.

What is claimed is:

1. In an automatic multi-spindle lathe having a spindle housing and a spindle drum rotatable about a horizontal axis in the housing for indexing movement through a plurality of working positions; a locking device for securing the spindle drum in each of the working positions of the latter comprising upper and lower locking pins, means slidably mounting said upper and lower pins in the spindle housing above and below, respectively, the spindle drum, with the longitudinal axes of said pins extending radially with respect to the axis of rotation of the spindle drum and lying in the vertical plane which passes through, and is parallel to said axis of rotation, the spindle drum having radially outward opening recesses disposed at the top and bottom of the drum in any of the working positions of the latter to register with and receive the radially inner ends of said upper and lower locking pins, respectively, said radially inner ends of the pins and said recesses registering with the latter in any of the working positions of the drum having lateral surfaces which converge at equal angles in the direction toward the axis of rotation of the spindle drum so that, when said upper and lower pins are urged in the direction of their longitudinal axes into said recesses at the top and bottom of the drum, said converging lateral surfaces of the pins and recesses come into close mutual contact to securely hold the drum against rotation from the working Position in which it is then disposed and to take up any lateral play in the rotational mounting of the drum in the spindle housing.

2. In an automatic mnlti-spindle lathe having a spindle housing and a spindle drum rotatable about a horizontal axis in the housing for indexing movement through a plurality of Working positions; a locking device for securing the spindle drum in each of the working positions of the latter comprising upper and lower locking pins, means slidably mounting said upper and lower pins in the spindle housing above and below, respectively, the spindle drum, with the longitudinal axes of said pins being in vertical alignment with each other and extending radially with respect to the axis of rotation of the spindle drum, the spindle drum having a circularly arranged series of radially outward opening recesses which are circumferentially spaced apart so that, in each working position of the drum, recesses of said series are disposed at the top and bottom of the drum and there register with and receive the radially innerends of said upper and lower locking pins, respectively, said radially inner ends of the pins and said recesses registering with the latter in any of the working positions of the drum having lateral surfaces which converge at equal angles in the direction toward the axis of rotation of the spindle drum so that, when said upper and lower pins are urged in the direction of their longitudinal axes into said recesses at the top and bottom of the drum, said converg ing lateral surfaces of the pins and recesses come into close mutual contact to securely hold the drum against rotation from the working position in which it is then disposed and to take up any lateral play in the rotational mounting of the drum in the spindle housing.

3. In an automatic multi-spindle lathe having a spindle housing and a spindle drum rotatable about a horizontal axis in the housing for indexing movement through a plurality of working positions; a locking device for securing the spindle drum in each of the working positions of the latter comprising upper and lower locking pins, means slidably mounting said upper and lower pins in the spindle housing above and below, respectively, the spindle drum, with the longitudinal axes of said pins being in vertical alignment with each other and extending radially with respect to the axis of rotation of the spindle drum, the spindle drum having a circularly arranged series of radially outward opening recesses which are circumferentially spaced apart so that, in each working position of the drum, recesses of said series are disposed at the top and bottom of the drum and there register with and receive the radially inner ends of said upper and lower locking pins, respectively, said radially inner ends of the pins and said recesses registering with the latter in any of the working positions of the drum having lateral surfaces which converge at equal angles in the direction toward the axis of rotation of the drum, and relatively strong spring means and relatively weak spring means acting against said upper and lower pins, respectively, to urge the latter into the recesses registering therewith in any of the working positions of the latter so that said converging lateral surfaces of the pins and of the recesses come into close mutual contact to securely hold the drum against rotation from the working position in which it is then disposed and to take up any lateral play in the rotational mounting of the drum in the spindle housing, While the preponderance of the spring means acting against said upper pin cooperates with the weight of the drum to urge the latter downwardly, thereby to take up any vertical play in the rotational mounting of the drurn.

4. In an automatic multi-spindle lathe, a locking device as in claim 3; wherein said upper and lower locking pins are of polygonal cross-section.

5. In an automatic multi-spindle lathe, a locking device as in claim 3; wherein said upper and lower locking pins have circular cross-sections.

6. In an automatic multi-spindle lathe, a locking device as in claim 3; further comprising means operative to withdraw said upper and lower pins from the related recesses during the indexing movement of the spindle drum from one working position to the next succeeding working position, and being eifective, upon arrival of the drum at the latter position, to first release said lower locking pin, acted upon by said relatively weak spring means, for initial engagement in the recess then disposed at the bottom of the drum for laterally positioning the lower part of the drum and, thereafter, to release said upper locking pin, acted upon by said relatively strong spring means, for laterally positioning the upper part of the drum and for removing vertical play from the rotational mounting of the drum.

References Cited in the file of this patent UNITED STATES PATENTS 197,358 Garrabrant Nov. 20, 1877 1,511,447 Drissner Oct. 14, 1924 1,669,124 Graves May 8, 1928 2,118,024 Potter May 17, 1938 2,633,777 Hoern Apr. 7, 1953 FOREIGN PATENTS 103,519 Great Britain Ian. 29, 1917 

